500/400/220 kV Akhaltsikhe Substation was officially commissioned on December 10, 2013. Construction of this substation was implemented under the framework of the Black Sea Transmission Network (“BSTN”) Project, which besides this facility, includes several other important components, e.g. construction/rehabilitation of overhead transmission lines (OHLs) “Vardzia 500” and “Zekari 500” interconnecting Akhaltskhe, Zestaponi and Gardabani Substation, as well as the construction of the new 400 kV OHL from Akhaltsikhe Substation to Georgia-Turkey border. These project works were divided in three contractual packages, namely, in Akhaltsikhe Substation, SIEMENS Austria constructed 500/400/220 kV sides , and SIEMENS Germany installed two HVDC Back-to-Back links each of 350 MW capacity, while construction/rehabilitation of OHLs was completed by KEC International (India).
The total contract price of 500/400/220 kV Akhaltsikhe Substation and back-to-back station amounted to Euro 158,8 million. The BSTN Project was financed using the loans of European Bank for Reconstruction and Development (EBRD), and the European Investment Bank (EIB), amounted to 80 million Euros each, and the 100 million Euro loan of the German Reconstruction Credit Bank (KFW). The Government of Georgia provided co-financing contribution of 53 million Euros, and Euro 8 million was granted by the Neighborhood Investment Facility (NIF) of EU. The works commenced on September 1, 2010 and were completed in April 2013. Commissioning tests of the back-to-back station (HVDC links) were performed in the end of November, 2013.
Georgia is the first country in the Caucasus Region where the HVDC back-to-back links are installed. So far such HVDC technologies have been implemented only in a few power systems around the globe. Each HVDC link includes rectifier and inverter stations, where 500 kV alternating current is converted into direct current, and again into alternating current, but with voltage of 400 kV that shall be supplied to Turkey without causing any disturbances or contingencies to the Turkish high voltage power system. In overall, the BSTN Project is of a great importance for ensuring sound operation of the entire Georgian power system. As it finals result, the Project contributes significantly to improved stability of the national electric power network, more reliable power supply of the South Georgia’s regions, and reduction of electricity losses, as well as provides effective opportunities for exporting to Turkey the surplus electricity generated in the country during summer period, and third countries’ electricity transit.